1. Field of the Invention
The present invention relates to a universal wireless communication system in which an available radio frequency spectrum is divided among at least a first and a second wireless subsystem, the first wireless subsystem comprising at least a first radio base station and a first plurality of wireless communication stations, and the second wireless subsystem comprising at least a second radio base station and a second plurality of wireless communication stations. Such a universal wireless communication system can comprise a plurality of wireless subsystems such as a terrestrial cellular or cordless radio system, a wireless local area network, a satellite system, or any other suitable wireless communication subsystem. The subsystems are able to operate independent of each other.
The present invention further relates to a transmission protocol, to a wireless communication station, and to a radio base station for use in such a system.
2. Description of the Related Art
A universal wireless communication system of the above kind is generally known from many publications about universal wireless communication systems, e.g., from the article "Third Generation Mobile--UMTS and FPLMTS", D. MacFarlane, 7th World Telecommunication Forum, Technology Summit, Vol. 2, pp. 185-188, ITU, Geneva, 3-11 October 1995. In such a future system and also in existing systems where a number of operators of either a private or a public wireless subsystem share an available frequency band radio resources are becoming scarce so that there is a need to make an efficient use of such radio resources. On the other hand, from a commercial point of view inter alia, it is highly desirable to operate wireless communication stations in the system such that energising means comprised in such a wireless communication station are being used efficiently, i.e., given the environmental circumstances, the wireless communication station should use as less power as possible. If many subscribers are present in the various subsystems, a operating wireless communication station, signals transmitted by the stations on an RF carrier cause interference to signals on neighbouring RF carriers or radio bands. For making an efficient use of the available frequency spectrum, particularly at inter-subsystem-boundaries, it is thus highly desirable to operate the system such that an optimum is achieved as to reducing interference and an economic operation of wireless communication stations.
It is an object of the present invention to provide a universal wireless communication system of the above kind making an efficient use of the available frequency spectrum while at the same time operating the wireless communication stations in an economic way as regards power consumption.
To this end the according to the present invention is characterised in that for operating the wireless communication system up to the limits of spectral band while at the same time allowing wireless communication stations to operate such that minimal power consumption is obtained under acceptable transmission conditions, the wireless communication system comprises a transmission protocol for adapting a spectral transmission characteristic of a wireless communication station comprising the following steps:
a) a radio base station of one of the wireless subsystems determines whether a wireless communication station of the other wireless subsystem is causing adjacent channel interference in a channel of the one wireless subsystem, whereby the wireless communication station of the other subsystem is identified by said radio base station, PA1 b) the radio base station of the one wireless subsystem issues a command to the wireless communication station of the other wireless subsystem in accordance with the determined interference situation, and
the identified wireless communication station adjusts its spectral transmission characteristic from a first to a second characteristic in accordance with the command. The present invention is based upon the insight that individual control of the spectral transmission spectrum of an interfering wireless communication station in one subsystem by a system resource of another subsystem achieves a better overall interference control in the system and achieves better overall power saving in the wireless communication stations in the system than with an uncoordinated transmission spectrum shaping. Furthermore, such an interference bandwidth/energy adjustment does not affect the information bandwidth or other RF characteristic. In the event of a cellular and cordless radio system as subsystems such subsystems can use adjacent frequency bands while applying wide band CDMA or wide band TDMA carriers without any further mutual coordination between such subsystems beyond the issuing of the command when an interferer is recognized from a wireless communication station being operated in a neighbouring frequency band. Power consumption in a wireless communication system can typically be reduced when the wireless communication station is operated in a non-congested system. With the transmission protocol according to the present invention RF carriers can be packed densely so that the spectrum efficiency is improved.